Tantalum and niobium compounds and process for preparing same



United States Patent poration of Virginia No Drawing. Filed Oct. 28, 1963, Ser. No. 319,533 21 Claims. (Cl. 260-429) This application is a continuation-in-part of the application of Serial No. 189,291, filed April 23, 1962, and now abandoned.

This invention relates to a catalytic process for the preparation of organometallic compounds. More specifically, the invention relates to a catalytic process for forming alkali and alkaline earth metal-etherate salts of Group VB metals having an atomic number of at least 41 in which the Group VB metal is present in the anion portion of the compound and is coordinately bonded to six carbonyl groups. The catalyst employed in the process is a material containing an iron-subgroup metal.

An object of this invention is to provide a novel process for preparing organometallic compounds of niobium and tantalum. A further object is to provide a process for producing stable alkali metal and alkaline earth metalethereate salts of tantalum and niobium hexacarbonyl anions in yields unattainable prior to this invention. Another object is to provide a catalyst which enhances the yield of alkali and alkaline earth metal-etherate salts of niobium and tantalum. Additional objects will become apparent from the following discussion and claims.

The objects of this invention are accomplished by providing a process in which a reducing metal, which is an alkali metal or an alkaline earth metal is reacted with a niobium or tantalum salt in the presence of an ether and a catalytic quantity of an iron-subgroup metal-containing material under carbon monoxide pressure. The process forms the alkali or alkaline earth metal-etherate salts of the niobium or tantalum hexacarbonyl anion.

A preferred embodiment of my invention is a process for the preparation of alkali and alkaline earth metaletherate hexacarbonyl niobates and hexacarbonyl tantalates which comprises reacting a metal selected from the class consisting of alkali and alkaline earth metals, an inorganic salt of a Group VB metal of atomic number of at least 41, a saturated, unsubstituted ether having up to about 12 carbon atoms and having 2 to 3 oxygen atoms wherein the terminal radicals are alkyl radicals having from 1 to about 6 carbon atoms and the bridging groups are alkylene radicals having from 2 to 3 carbon atoms, and carbon monoxide under pressure, said process being carried out in the presence of a catalytic quantity of an iron subgroup-metal-containing material selected from the class consisting of iron subgroup metals, iron subgroup metal oxides, iron subgroup metal halides, iron subgroup metal carbonyls, and mixtures thereof.

The salts produced by my process are unusual in that they contain an anion having a charge of minus one in which the negative charge is centered about the niobium or tantalum metal atom. This fact makes the anion a potent reductant so that it can be readily employed in forming other compounds via oxidation-reduction reactions.

My process involves a catalyzed reaction between a reducing metal and a salt of a Group VB metal of atomic number of at least 41 in the presence of an ether and carbon monoxide under pressure. The alkali metals which may be employed as reductants are lithium, sodium, potassium, rubidium and cesium. The alkaline earth metals which may be employed are calcium, strontium, barium and magnesium. In addition, zinc or aluminum may be Patented Oct. 4, 1966 employed as the reducing metal. Preferably, the reducing metal is an alkali metal and most preferably it is sodium. Mixtures of the above reducing metals may be employed. For example, I can use a mixture of sodium and potassium as the reductant.

The reducing metal should be in a highly active form. Fluidized suspensions or dispersions of an alkali metal in an inert liquid are highly active and are preferred reactants. Examples of such suspensions are finely divided sodium or potassium in mineral oil or parafiin. Amalgams of the reducing metals are highly active and can be employed, if desired. A magnesium amalgam is a typical reactant of this type. Freshly prepared metalturnings which have a large surface area can also be employed.

Usually the reducing metal is employed in at least a \50 percent excess over that theoretically required to reduce the Group VB metal to a valence state of minus one.

A wide variety of ethers can be employed in this process. The ethers may have one or more ether oxygen atoms. Preferably, the ether is a bidentate or tridentate ether; that is, it contains two or three ether-oxygen atoms per molecule. However, monodentate ethers such as diethylether can be employed if desired. The bidentate and tridentate ethers are preferred because the salts containing them are more stable than the salts prepared from a monodentate ether. As evidence of the greater stability of the tridentate ether salts, I have found that sodium bis- (diethyleneglycol dimethylether) hexcarbonyl tantalate can be recrystallized from dietheylether without solvent exchange.

The exact nature of the radicals bonded to the oxygen atom or atoms is not critical provided that the radicals are stable under the reaction conditions employed and that they do not unduly retard the reaction by steric hindrance. Ethers that contain cyclic and alicyclic radicals are applicable.

Preferred radicals do not have reactive substituents which cause competitive side reactions. Typically, the radicals bonded to the ether oxygen atoms are unsubstituted hydrocarbon radicals; i.e., they are composed solely of carbon and hydrogen. Saturated hydrocarbon radicals, e.g., alkyl and alkylene radicals, are preferred. Typically, these radicals are a straight chain. However, ethers containing one or more branched chain radicals are applicable.

The bidentate and tridentate ethers are illustrated by the following formulas:

In the formulas, R" and R" represent bridging groups which are straight or branched chain alkylene radicals having from 2 to about 3 carbon atoms. The ethylene radical is the preferred bridging group. Preferred tridentate ethers have two ethylene radicals.

The radicals R and R are terminal groups having from 1 to about 6 carbon atoms. R and R may be alicyclic radicals having from 4 to 6 carbon atoms. However, ethers of this type are not preferred since they are not readily available. In the preferred ethers, R and R are straight or branched chain alkyl radicals. Ethers wherein R and R" are identical straight-chain radicals are highly preferred.

Ethers of the above types having up to about 16 carbon atoms, are preferred. Highly preferred ethers contain up to about 12 carbon atoms. The most preferred ethers contain up to about 8 carbon atoms.

Typical bidentate ethers that can be employed in this process include dimethoxyethane, diethoxyethane, dibutoxyethane, diisobutoxyethane, dipentoxyethane, 1,2-propy-leneglycol dimethylether, 1,2-propyleneglycol diethylether, l,3-propyleneglycol methylethylether, 1,3-propyleneglycol methylisopropylether, 1,3-propyleneglycol eth- 13 11; 1,3-propyleneglycol ylhexylether, hexylisopropylether,

1,3-propyleneglycol butylpentylether, 1,3-propyleneglycol met-hylbutylether, 1,3-propyleneglycol diethylether, 1,3- propyleneglycol dipropylether, 1,3-propyleneglycol dibutylether and the like.

Typical tridentate ethers that are applicable in this process include diethyleneglycol dimethylether, diethyleneglycol diethylether, diethyleneglycol diisopropylether, diethyleneglycol dibutylether, diethyleneglycol dihexyL ether, di-1,3-propyleneglycol dimethylether, di-l,3-propyleneglycol dibutylether, di-1,3-propy-leneglycol diisobuty1- ether, di-1,2-propyleneg1ycol diethylether, di-1,2-propyleneglycol dimethylether and the like.

Other applicable tridentate ethers include diethyleneglycol methylethylether, diethyleneglycol methylisopropylether, diethyleneglycol methylbutylether, diethyleneglycol ethylhexylether, diethyleneglycol propyl'butylether, 2,6,9- trioxaundecane and the like. Thus, when 30 moles of these ethers are contacted with two gram atoms of sodium, and 0.2 moles of tantalum pentachloride and carbon monoxide under a pressure of 3,000 p.s.i. at 110 C., and in the presence of a catalytic quantity of iron or iron carbonyl, the products are sodium bis(diethyleneglycol methylethylether) hexacarbonyl tantalate, sodium bis(diethyleneglycol methylisopropylether) hexacarbonyl tantalate, sodium bis(diethyleneglycol methylbutylether) hexaoarbonyl tantalate, sodium bis(diethyleneglycol ethyl hexy'lether) hexacarbonyl tantalate, sodium bis(diethyleneglycol propylbutylether) hexocarbonyl tantalate and sodium bis(2,6,9-trioxaundecane) hexacarbonyl tantalate, respectively.

The other ethers mentioned above react in a similar manner. When the above process is repeated using a bidentate ether, the product contains three ether molecules. A typical product of the process of this invention derived from a bidentate ether is sodium tris(1,3-propyleneglycol methylethylether) hexacarbonyl tantalate.

The ether is generally employed in a large excess since it functions as both a reactant and a solvent. It is preferred that the ether have a comparatively low toxicity, be compatible with a wide range of reducing metals, and be usable in large quantity without the use of elaborate safety precautions. The most preferred ethers are diethyleneglycol dimethylether and dimethoxyeth-ane.

The catalysts applicable in this process are iron subgroup metal-containing materials, e.g., compounds of iron, ruthenium, or osmium, the metals themselves, or mixture of the metals and other materials, mixtures of the compounds or mixtures of the compounds and metals. A wide variety of compounds of the iron subgroup metals (iron, ruthenium, and osmium) are suitable catalytic agents in the process of this invention. Oxides such as iron (II) oxide, iron (HI) oxide, osmium (IV) oxide and ruthenium (IV) oxide can be employed. Similarly, halides such as iron (III) chloride, osmium (IV) chloride, iron (III) bromide, ruthenium (IV) chloride and the like are applicable. Iron (III) sulfide and similar compounds of osmium and ruthenium are suitable catalysts. Similarly, carbonyl compounds of the iron-subgroup metals such as iron pentacarbonyl, ruthenium pentacarbonyl, osmium pentacarbonyl, iron enneacarbonyl and iron dodecacarbonyl can be employed. The carbonyl halides and hydrides, e.g., Fe (CO) Cl and Fe(CO) H are also suitable catalysts. Olefinic derivatives of the metal car- 'bonyls such as butadiene iron tricarbonyl, cycloheptatriene iron tricarbonyls, and methylcycloheptatriene ruthenium tricarbonyls can likewise be employed. Preferably, the metal is in an active form. Degreased metal powders and fresh turnings are preferred. The metals can also be employed in conjunction with other materials such as alumina, bismuth, nickel, copper, sulfur, or iodine.

Although not bound by any theory, it is believed that any iron-subgroup metal-containing material which will, under the conditions of the reaction employed, form catalytic quantities of the pentacarbonyls of iron, osmium i or ruthenium, or the alkali or alkaline earth metal derivatives thereof, such as Na Fe (CO) MgFe(CO) N-aHFe(CO) or the analogous derivatives of osmium and ruthenium, is a suitable catalyst.

The amount of catalyst employed is determined by several considerations. Catalytically active and economically feasible concentrations are preferred. Thus, amounts equivalent to 0.01 to 30 percent by weight of the tantalum or niobium salt are preferred. A highly preferred range is from about 0.05 to about 10 percent. (The above amounts of catalyst are expressed as weight of free iron, osmium or ruthenium.) Some commercial preparations of the tantalum and niobium halides contain catalytically active amounts of osmium compounds as impurities. When these salts are used it is not necessary to add additional catalyst. The amount of catalyst required is governed by the reactivity of the catalyst and of the re-. actants, and the conditions such as temperature and pressure. Catalysts that do not undergo extraneous, undesirable reactions with the products and/ or reactants and which are easily separable from the products are preferred.

As discussed above, the catalyst in the process of this invention is a material containing catalytic quantities of iron-subgroup metals, iron-subgroup oxides, iron-subgroup halides, iron-subgroup carbonyls and the like, and mixtures thereof. It has been found that mixtures such as iron carbonyl and iron (III) halides such as iron (HI) chloride and iron pentacarbonyl are very effective catalysts. We prefer to use this mixture in a weight ratio ranging from 1:10, (iron halide to iron carbonyl). A preferred range is 1:1.5 (iron halide to iron carbonyl). Other preferred catalysts are the iron-subgroup halides and ironsubgroup pentacarbonyls. The most preferred catalysts are osmium tetrachloride and iron pentacarbonyl.

The carbon monoxide pressure employed ranges between about 3,000 to about 8,000 p.-s.i. since within this range yields are maximized while reaction time is minimized.

My process may be carried out over a temperature range from about 60 C. to about 150 C. Higher temperatures than about 150 C. tend to increase the amount of decomposition occurring in the reaction and temperatures lower than about 60 C. tend to increase the reaction time beyond a practical limit. I prefer to use temperatures compatible with the products and reactants. Preferably, my process is carried out at a temperature of about C. since at this temperature,.yields are maximized while undesired side reactions are minimized. Generally, my process is carried out with agitation of the reaction mixture since it is found that this insures a more even reaction rate.

The time required for my process is not a truly independent variable, but is dependent to some degree upon the other process conditions employed. Thus, for example, if a relatively high temperature, a relatively high carbon monoxide pressure, a high degree of agitation, and an active catalyst are employed the reaction time will be reduced. If, on the other hand, a relatively low temperature, a relatively low carbon monoxide pressure, and slight agitation are used, the reaction time will be proportionately increased. In practice, the necessary reaction time is easily determined since one can trace the course of the reaction by observing the variation in carbon monoxide pressure in the reaction system. As the reaction proceeds, carbon monoxide is used in the reaction and a substantial pressure drop occurs. When the pressure ceases to drop, this 18 evidence that the reaction is completed and the reaction product can be discharged. In general, from about one to about 40 hours reaction time is sufiicient although, as stated above, other reaction times can be employed if the process conditions are varied accordingly.

The niobium and tantalum-containing starting materials react with the ether solvent to form a product which does not readily form the desired alkali metal or alkaline earth metal-etherate niobium or tantalum hexacarbonyl salt."

Previously, this undesirable eifect was eliminated by rapidly adding the niobium or tantalum reactant to a mixture of the reducing metal and ether to form the desired product before the undesired side reaction could take place. A decided advantage gained by the present process is that the order of mixing of the reactants is no longer of paramount importance. Thus, if it is desired, the alkali metal can be added to a mixture of the ether and tantalum or niobium reactant.

Vanadium salts do not react rapidly with the ether solvent. The beneficial effects of the catalyst are not nearly as pronounced with vanadium as when niobium or tantalum salts are employed. For these reasons, it is believed that the catalysts found useful in this invention diminish the formation of the undesirable niobium and tantalum salt-ether complexes.

Of the niobium or tantalum metal salts, some are preferred for use in my process. The halides, and particularly the chlorides, are preferred reactants since they are relatively cheap and readily available. Examples are tantalum pentachloride and niobium pentachloride.

The products formed from my process are readily separated from the liquid reaction mixture. The reaction product is generally first filtered to remove any insoluble residue including any excess reducing metal. After this operation, the products are readily precipitated from the filtrate by adding to it a hydrocarbon such as petroleum ether, nonane, hexane, or the like. After the product has precipitated, it can then be separated by means of filtration, decantation of the liquid, centrifugation and the like.

To further illustrate my process, as defined above, there are presented the following examples in which all parts and percentages are by weight unless otherwise indicated.

EXAMPLE I A sealed glass tube containing 66.0 grams of commercial tantalum pentachloride containing OsCl (0.1 percent as osmium metal) was placed in a reaction vessel in such a fashion that the tube would be broken when the agitator was started. There was then added to the reaction vessel a suspension comprising 51.0 grams of sodium in 500 ml. of diethyleneglycol dimethylether. The reaction vessel was then closed and pressurized with carbon monoxide to a pressure in the order of 1,500 to 2,000 p.s.i. When the pressure reached this point, the glass tube cracked and the agitator was started. Following this, the pressure was increased further to 3,000 p.s.i. and the reaction vessel was heated slowly -to 100 C. After heating for one hour at about 100 C. a pressure drop was noted which indicated that carbon monoxide was being taken up in the reaction. Heating at 100 C. was continued for another 12 hours and the reaction vessel was then kept at 100 C. for an additional 7 hours during which time no further additional carbon monoxide uptake was observed. The total reaction time was 22 hours. The reaction vessel was then vented and the product was discharged and filtered to remove excess sodium. The resulting clear yellow solution showed one sharp band in the infrared region at 5.42 microns. Addition of the filtered solution to an excess of stirred petroleum ether gave a deep yellow precipitate of sodium bis(diethyleneglycol dimethylether) hexacarbonyl tantalate. The total yield of product was 37.2 grams. The deeply colored yelow solid was air sensitive. The material was stable under nitrogen and only slightly sticky at room temperature. It was soluble in water giving a pH of 8 and formed an insoluble yellow precipitate of tetramethylammonium hexacarbonyl tantalate when added to a solution of tetramethylammonium bromide. On analysis there was found: C, 34.1; H, 4.63; Na, 3.88; T-a, 27.9. Calculated for C H NaO Ta: C, 33.76; H, 4.41; Na, 3.60; Ta, 28.25 percent.

Similarly, potassium bis(diethyleneglycol dibutylether) hexacarbonyl tantalate and sodium tris(dimethoxyethane) hexacarbonyl tantalate are prepared when diethyleneglycol dibutylether and dimethoxyethane are used in place of diethyleneglycol dimethylether.

When the procedure of Example I was carried out in the absence of an iron-subgroup metal-containing material, using carefully purified sample of tantalum (V) chloride (which was free of osmium and other iron-subgroup metalcontaining materials) as the reactant, a much lower yield of sodium bis (diethyleneglycol dimethylether) hexacarbonyl tantalate was prepared. This illustrates the catalytic properties of an iron-subgroup metal-containing material.

The effectiveness of a catalyst in the process of this invention is also apparent from a comparison of the following two examples.

EXAMPLE II In the same manner as in Example I, 39.0 grams of carefully purified niobium pentachloride were reacted with 40 grams of sodium in the presence of diethyleneglycol dimethylether solvent. The niobium pentachloride was added to the reaction vessel in a glass tube which was broken after the vessel had been pressurized with carbon monoxide. After heating at C. under a carbon monoxide pressure of 4,000 p.s.i. for about 20 hours, the reaction vessel was discharged. The product was separated from the reaction mixture in the manner employed in Example I. A small yield of sodium bis(diethyleneglycol dimethylether) hexacarbonyl niobate was obtained.

EXAMPLE III A sealed frangible tube containing 55 grams of niobium pentachloride was inserted into a stainless steel autoclave equipped with heating and stirring means. The tube was so placed that it would be broken up on activation of the stirrer. Sodium metal, 55.2 grams, suspended in 800vparts of diethyleneglycol dimethylether and 2 grams of anhydrous ferric chloride and 3 ml. of iron pentacarbonyl were charged into the clave, The vessel was pressured to 4,000 p.s.i. with carbon monoxide. Agitation was commenced and the mixture heated at C. for 19 hours. The discharged mixture was filtered to remove the solid-s and the clear deep yellow diethyleneglycol dimethylether solution was worked up as in ExampleI by treatment with petroleum ether to yield 29 parts of sodium diethyleneglycol dimethylether niobium hexacarbonyl. The yield was 26.2 percent. The yellow solid decomposed slowly in air and melted at l44146 C. under nitrogen. Analysis calculated for: C H NaNbO C, 39.2; H, 5.1; Nb, 16.8. Found: C, 38.3; H, 5.25; Nb, 16.5.

High yields of magnesium and calcium salts of hexacarbonyl niobate can be prepared when these metals are substituted for the sodium metal used in Example III. These salts contain diethyleneglycol dimethylether. Similarly, dioxane, and dibutylether can be substituted for diethyleneglycol dimethylether. Corresponding etherated sodium salts of hexacarbonyl niobate are prepared.

When the process of Example III is repeated except that diethyleneglycol diethylether, diethyleneglycol dibutylether, di-1,3-propyleneglycol dimethylether, or (ii-1,2- propylen'eglycol dibutylether is employed, the product is sodium bis(diethyleneglycol diethylether) hexacarbonyl niobate, sodium bis(diethyleneglycol dibutylether) hexacarbonyl niobate, sodium bi-s(di-1,3-propyleneglycol dimethylether) hexacarbonyl niobate, sodium bis(di-1,2- propyleneglycol dibutylether) hexacarbonyl niobate, respectively. Similar results are obtained when 5 grams of anhydrous ferric chloride is used in place of the mixture of ferric chloride and iron pentacarbonyl. Similar results are obtained when iron pentacarbonyl is employed as a catalyst.

When the above reactions are carried out in the absence of an iron subgroup metal-containing material, the yields of product are diminished.

7 EXAMPLE IV On agitation, the frangible vial is broken, and the. niobium pentabromide is released into the system. After heating for 30 hours at 110 C., the reaction vessel is cooled and excess oarbon'monoxide' pressure is released.

by venting. The reaction product is then discharged,

S TCII grams of ruthenium Pentacarbonyl is added filtered, and petroleum ether is added to the filtrateto to the mixture which is then pressurized to 5,000 p.s.i. produce a precipitate f potassium tris(diethyleneglycol with carbon monoxide. The reaction vessel is then heated dimethylether) h b l niobate,

to 100 C. at time the agitator is started and the Th o ound produ ed my proces are quite usefrangible vial is broken so as to release the tantalum 10 an in metal plating li ti ns, In order to use my pentabromide reactant. After heating for 40 hours at compounds in metal plating, h are fi converted to 100 C. the reaction vessel is cooled and vented. The a tetraalkylammoninm h z rb l Group VB metal' reaction product is filtered, petroleum ether is added to salt This is i tl aceomplished by reacting a the filtrate and a good yield of a magnesium dioxane hexatetraalkylammonium compound h as h carbonyl tantal'ate salt is Obtainedammonium bromide with the alkali or alkaline earth When the reaction is repeated using tetfahydrofuran metal-etherate salt of the hexacarbonyl Group VB metal in Place of diOXaIle, the Product is a magnesium tetraanion. As shown previously in Example I, there is obhydl'ofuran hexacarbonyl tantalate Sam tained from this reaction the tetraalkylammoniurn hexa- EXAMPLE, V carbonyl Group VB metal salt (in that case tetramethylammonium hexacarbonyl tantalate). These salts can be To l'eactlon Vessel Contammg grams of decomposed so as to deposit a metal-containing coating Fe(co)4c12, 8 moles of a mineral on spspenslon 9 on a surface which it is desired to plate. Since the tetrasodium and 18 moles of ethyleneglycol dlethylefl? 1S alkylammonium salts are not volatile, theplating is acadded one mole of tantalum pentachloride which is encomplished by bringing a heated object, whose tempera- Closed in a frangible Vial- The reaction vessel 15 then 25 ture is above the decomposition temperature of the tetra- Pl'Pssllrized to 4,000 P- with carbon monoxide and alkylammonium salt, into contact with the salt. This the Vial is broken by Starting the agitation After, results in decomposition of the saltand the formation of ing at 100 C. for 36 hours, the reaction vessel is disa Group VB metahcontaining coating on h h t d charged and a good yield of sodium tris(ethyleneglycol object diethylether) hexacarbonyl tantalate is separated from Another method by hi h l i can b li h d the reaction Product by the Procedure used the Prevl' is to coat the surface of the object to be plated with the 011s lf tetraalkylammonium salt of the Group VB metal hexa- In a slmllar manner ethyleneglycol dunethylethel" carbonyl anion and then to heat the coated object to a. ethyleneglycol diisopropylether: ethylerlfitglycol f i temperature above the decomposition temperature of the ether, and ethyleheglycol dihexylethel' Yield sodlum ms tetraalkylammonium salt. This also results in forming (ethyleneglycol dimethyletherl hexacarbonyl tantalate, a meta1 containing coating on the object to be 1 sodium tr1s(ethyleneglycol dnsopropylether) hexacar- To further illustrate my method for forming coatings bonyl tantalate, sodium tris(ethyleneglycol dibutylether) containing a Group VB metal, there is presented the hexacarbonyl tantalate, and sodium tris(ethyleneglycol following example. dihexylether) hexacarbonyl tantalate, respectively.

Similarly, diethylether and dihexylether yield sodium 40 EXAMPLE VII hexakis(diethylether) hexacarbonyl tantalate and sodium A glass cl th b d weighing one gram is dried for one hexakis(dihexylether) hexacarbonyl tantalate, respech i a oven at 150 C, It is then covered with a tively. thin layer of tetramethylammonium hexacarbonyl tan- Other examples of the use of various catalysts suitable talate and is placed in a container which is devoid of air. for my process are found in the following table. The container is heated to a temperature of 500 C. for

TABLE Metal Reaetant Catalyst Solvent Product Tantalum peutachl0ride Iron oxide Diglyme Sodium bis(diglyme)l1exacarbonyl tantalate.

Osmlum tetraoxide Do. Ruthenium tetraoxide. Do. Iron powder Do. Ruthenium powder D Iron powder and alumina Potassium bis (diethyleneglycol dibutylether) hexaearbonyl niobate.

Iron (III) bromide Do. Iron (III) sulfide Do. Iron pentacarbonyl Do. do Ruthenium pentacarbonyL. Do.

Tantalum pentachloride Ir0n tetracarbonyl dihy- A calcium diglyme salt of liexadride. carbonyl tantalate. Strontium do Iron tetracarbonyl dlehlo- A strontium diglyme salt of ride. hexacarbonyl tantalate. Magnesium Iron e neacarbonyl do A magnesium diglyrne salt of hexaearbonyl tautalate. Magnes um amalgam Butadiene Iron tricarbonyL- do Do. strontium amalgam- Oycl heptatriene iron trido A strontium diglyme salt of carbonyl. hexaoarbonyl tantalate.

1 Diglyme=Diethyleneglycol dimethylether.

EXAMPLE VI one hour after which time it is cooled and opened. The cloth is coated with a tantalum-containing coating, has

a metallic grey appearance, and exhibits a slight gain in weight.

As shown by the previous example, the compounds formed from my process can be converted to their tetraalkylammonium salts which can be utilized in forming with carbon monoxide, heated to 110 C. and agitated. metal-containing coatings. These coatings are not only decorative but serve also to protect the underlying substrate material from corrosion. The novel compounds produced by the process of this invention are useful chemical intermediates.

Having fully defined the novel compounds of my invention, their mode of preparation and their utility, I desire to be limited only within the lawful scope of the appended clams.

I claim:

1. A process for the preparation of alkali and alkaline earth metal-etherate salts of tantalum and niobium hexacarbonyl anions, said process comprising reacting (a) a metal selected from the class consisting of alkali and alkaline earth metals,

(b) an inorganic salt of a Group VB metal of atomic number of at least 41,

(c) a saturated, unsubstituted ether having up to about 12 carbon atoms and having 2 to 3 ether oxygen atoms, wherein the terminal radicals are alkyl radicals having from 1 to about 6 carbon atoms and the bridging groups are alkylene radicals having from 2 to 3 carbon atoms, and

(d) carbon monoxide under pressure; said process being carried out in the presence of a catalytic quantity of an iron subgroup-metal-containing material selected from the class consisting of iron subgroup metals, iron subgroup metal oxides, iron subgroup metal halides, iron subgroup metal carbonyls, and mixtures thereof.

2. The process of claim 1 wherein the carbon monoxide pressure is from about 3,000 to about 8,000 p.s.i.

3. The process of claim 2 carried out at a temperature from about 60 C. to about 150 C.

4. The process of claim 3 wherein the temperature is about 100 C.

5. The process of claim 1 in which the catalyst is a mixture of iron halide and iron pentacarbonyl.

6. The process of claim 5 in which the catalyst is a mixture of iron chloride and iron pentacarbonyl.

7. A process for the preparation of alkali and alkaline earth metal-etherate salts of tantalum and niobium hexacarbonyl anions, said process comprising reacting (a) a metal selected from the class consisting of alkali and alkaline earth metals,

(b) an inorganic salt of a Group VB metal of atomic number of at least 41,

(c) an ether having up to about 12 carbon atoms and having the formula wherein R and R are alkyl radicals having up to about 6 carbon atoms, and (d) carbon monoxide under pressure;

said process being carried out in the presence of a cataly-- tic quantity of an iron-subgroup metal-containing material selected from the class consisting of iron subgroup metals, iron subgroup metal oxides, iron subgroup metal halides, iron subgroup metal carbonyls, and mixtures thereof.

8. Process of claim 7 wherein said ether is dimethoxyethane.

9. A process for the preparation of alkali and alkaline earth metal-etherate salts of tantalum and niobium hexacarbonyl anions, said process comprising reacting (a) a metal selected from the class consisting of alkali and alkaline earth metals,

(b) an inorganic salt of a Group VB metal of atomic number of at least 41,

(c) an ether having up to about 12 carbon atoms and having the formula wherein R and R are alkyl radicals having from 1 to about 6 carbon atoms; (d) carbon monoxide under pressure; said process being carried out in the presence of a catalytic quantity of an iron-subgroup metal-containing material selected from the class consisting of iron subgroup metals, iron subgroup metal oxides, iron subgroup metal halides, iron subgroup metal carbonyls, and mixtures thereof.

10. The process of claim 9 wherein said ether is diethyleneglycol dimethylether.

11. The process of claim 10 wherein said alkali metal is sodium.

12. The process of claim 11 wherein the carbon monoxide pressure is from about 3,000 to about 8,000 p.s.i. 13. A process for the preparation of sodium-etherate salts of tantalum and niobium hexacarbonyl anions, said process comprising reacting sodium with (1) an ether having up to about 12 carbon atoms, said ether selected from the class consisting of ethers having the formula wherein R and R are alkyl radicals having from 1 to about 6 carbon atoms;

(2) an inorganic salt of a Group VB metal of atomic number of at least 41; and

(3) carbon monoxide under pressure of from about 3,000 to 8,000 p.s.i.;

in the presence of a catalytic amount of an iron-subgroup metal-containing material selected from the class consisting of iron subgroup metals, iron subgroup metal oxides, iron subgroup metal halides, iron subgroup metal carbonyls, and mixtures thereof, and at a temperature of about C. and subsequently separating the sodiumetherate salt, thereby produced, from the reaction mixture by treating said reaction mixture with a hydrocarbon to remove said sodium-etherate salt from solution.

14. The process of claim 13 wherein said catalyst is a mixture of iron halide and iron pentacarbonyl.

15. The process of claim 14 wherein said catalyst is a mixture of iron chloride and iron pentacarbonyl.

16. Process for the preparation of sodium bis(diethyleneglycol dimethylether) hexacarbonyl tantalate, said process comprising reacting sodium, tantalum pentachloride and diethyleneglycol dimethylether under pressure of carbon monoxide in the presence of osmium tetrachloride.

17. The process of claim 16 carried out at about 100 C.

18. The process of claim 17 wherein the carbon monoxide pressure is from about 3,000 to about 8,000 p.s.i.

19. Process for the preparation of sodium bis(diethyl eneglycol dimethylether) niobium hexacarbonyl, said process comprising reacting sodium, niobium pentachloride and diethyleneglycol dimethylether under pressure of carbon monoxide and in the presence of a catalytic amount of a mixture of anhydrous ferric chloride and iron pentacarbonyl.

20. The process of claim 19 carried out at a temperature of about 100 C.

21. The process of claim 20 wherein the carbon monoxide pressure is from about 3,000 to about 8,000 p.s.i.

No references cited.

TOBIAS E. LEVOW, Primary Examiner. T. IAPALUCCI, Examiner. 

1. A PROCESS FOR THE PREPARATION OF ALKALI AND ALKALINE EARTH METAL-ETHERATE SALTS OF TANTALUM AND NIOBIUM HEXACARBONYL ANIONS, SAID PROCESS COMPRISING REACTING (A) A METAL SELECTED FROM THE CLASS CONSISTING OF ALKALI AND ALKALINE EARTH METALS, (B) AN INORGANIC SALT OF A GROUP VB METAL OF ATOMIC NUMBER OF AT LEAST 41, (C) A SATURATED, UNSUBSTITUTED ETHER HAVING UP TO ABOUT 12 CARBON ATOMS AND HAVING 2 TO 3 ETHER OXYGEN ATOMS, WHEREIN THE TERMINAL RADICALS ARE ALKYL RADICALS HAVING FROM 1 TO ABOUT 6 CARBON ATOMS AND THE BRIDGING GROUPS ARE ALKYLENE RADICALS HAVING FROM 2 TO 3 CARBON ATOMS, AND (D) CARBON MONOXIDE UNDER PRESSURE; SAID PROCESS BEING CARRIED OUT IN THE PRESENCE OF A CATALYTIC QUANTITY OF AN IRON SUBGROUP-METAL-CONTAINING MATERIAL SELECTED FROM THE CLASS CONSISTING OF IRON SUBGROUP METALS, IRON SUBGROUP METAL OXIDES, IRON SUBGROUP METAL HALIDES, IRON SUBGROUP METAL CARBONYLS, AND MIXTURES THEREOF. 